Oral implantation devices are well known in the art and a pertinent example of the prior art is U.S. Pat. No. 3,465,441, issued Sept. 9, 1969, to Linkow. This patent depicts several embodiments of a bladevent implant on which the abutment post bearing a tooth is directly joined to the bladevent body portion which becomes embedded in the cancellous bone of the jaw.
The present invention has for its objective to improve upon the above prior art arrangement through the provision of a combination type implant having a bladevent body for insertion into the spongy jaw bone and a subperiosteal portion attached to the bladevent portion at two end extremities of the latter only and otherwise isolated therefrom. The abutment post is directly attached at the center of the subperiosteal portion or frame of the implant and is therefore isolated from and only indirectly connected with the bladevent body.
Among the features and advantages of the above combination oral implant are the following.
(1) The blade portion of the implant is completely surrounded by bone except for its two slender end elements which are joined with the opposite end portions of the subperiosteal component of the implant.
(2) All of the subperiosteal portion of the implant lies on top of the bone but below the oral mucosa and periosteum except for the implant abutment post which protrudes into the oral cavity.
(3) A most important distinction between the invention and other oral implants is that the abutment post is not attached directly to the implant blade, but is indirectly attached through the subperiosteal part of the implant, the latter being joined to the blade at two local end points. This permits the bone to grow completely over the top of the blade except at the two small areas where the blade and subperiosteal portions are joined.
(4) An important result of the feature immediately above is that the combination implant can have a shallower sulcus depth and less epithelial invagination. That is, oral epithelium cannot grow down along the implant abutment post and around the blade portion, as opposed to what can take place with implants in which the abutment post is directly attached to the blade portion.
(5) The blade portion of the implant can be placed in the bone at any angle and still have the implant posts parallel to the tooth abutments without bending the neck of the implant.
(6) There is greater vertical and lateral stability for the implant when installed. The combination structure tends to prevent sinking of the blade into the cancellous bone after long term function.
(7) Slightly less vertical alveolar process is required for implant success due to added stability afforded by the subperiosteal framework, making it easier to avoid the mandibular canal or the maxilary sinus.
(8) The head of the combination implant can be positioned mesiodistally exactly where needed for proper occlusion.
Other features and advantages of the invention will become apparent during the course of the following description.